Spotlight SAR image generation based on strip mode focusing techniques

The authors present a new solution for spotlight SAR data processing based on strip mode focusing techniques. The starting point of the proposed approach is a strip mode azimuth compression operation carried out on the raw signal; this operation produces a sequence of azimuth compressed images of the illuminated area, each one corresponding to one replica of the folded azimuth spectrum and therefore referred to as image replicas. Following this operation the residual focusing of each image replica is independently performed via a standard strip mode processing approach carried out up to the final inverse azimuth Fourier transform; the unfolded azimuth spectrum is finally computed by combining the spectra of the focused image replicas and an overall azimuth inverse FT allows to achieve the fully focused spotlight image. Presented experiments confirm the validity of the proposed approach.